Structural engineering of MXenes towards high electrochemical performance in supercapacitors

Supercapacitors (SCs) stand out among various energy storage devices for their high power density and long-term cycling stability stability. As a new two-dimensional material, MXenes has become a research hotspot in recent years because of its unique structure and rich surface functional groups. Compared to other materials, MXenes are more promising in supercapacitors due to their tunable precursor, structural stability, and excellent electrical conductivity. The electrochemical performance of MXene materials is poor and the stacking situation severely limits its application, so different modification strategies are used to improve the electrochemical performance of MXene materials. Since the modification strategy of MXene electrode materials often involves increasing the ion transport channels to expose more active sites, the packing density will also be affected to different degrees. Therefore, how to achieve a balance between high volumetric capacitance and rapid ion transport has become a key issue for the application of MXene-based supercapacitors in wearable devices and micro-devices. In this paper, the latest progress in the preparation methods and modification strategies of MXenes in recent years is reviewed, aiming to achieve both high volumetric capacitance and high ion transport, which is helpful to expand the application of MXene-based supercapacitors in microdevices and wearable devices.